SpamAssassin - Use this program to "Unspam" your mailbox(es).
Postfix - Postfix is a mail transfer agent (MTA) that routes and delivers electronic mail.
MailScanner - MailScanner is a open source email security system design for Linux-based email gateways.
Sendmail - Sendmail is a general purpose internetwork email routing facility that supports many kinds of...
Rspamd - Rspamd is an advanced spam filtering system that allows evaluation of messages by a number of rules...
Exim - Exim is a message transfer agent (MTA) developed at the University of Cambridge for use on Unix systems connected to the Internet.